I've made a scenerio in which you have a class called Man, which the player can control and a class called Enemy.
They're both shooting at each other, but when the Man is killed and the Enemy tries to shoot, there occurs an error:
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
at java.util.ArrayList.rangeCheck(ArrayList.java:653)
at java.util.ArrayList.get(ArrayList.java:429)
at Enemy.randomShoot(Enemy.java:59)
at Enemy.act(Enemy.java:29)
at greenfoot.core.Simulation.actActor(Simulation.java:604)
at greenfoot.core.Simulation.runOneLoop(Simulation.java:562)
at greenfoot.core.Simulation.runContent(Simulation.java:221)
at greenfoot.core.Simulation.run(Simulation.java:211)
I thought that this was caused by the fact that if the Enemy shoots a bullet, the bullet will turn towards the x and y-coordinates of the Man, but as there is no Man anymore, it won't be able to turn towards its coordinates. So I made the Enemy only shoot if getWorld().getObjects(Man.class) != false.
But the error still occurs when the man is killed.
So here are the pieces of code (possibly) involved in the problem:
(the class Movers is only the superclass of Bullet, Enemy and Man)
Movers code:
Bullet code:
Man code:
And the Enemy code:
public Movers()
{
}
public void shoot(int toX, int toY, int fromX, int fromY, String sender)
{
String target = "unknown";
if (sender == "Man")
{
target = "Enemy";
}
else if (sender == "Enemy")
{
target = "Man";
}
getWorld().addObject ( new Bullet(toX, toY, sender, target), fromX, fromY );
}
public boolean canGetWorldManEnemy()
{
if (getWorld() != null)
{
if (getWorld().getObjects(Enemy.class) != null && getWorld().getObjects(Man.class) != null)
{
return true;
}
else
{
return false;
}
}
else
{
return false;
}
}private int speed;
private int goToX;
private int goToY;
private String myTarget;
private String mySender;
private boolean isTouchingBlock = false;
private boolean hasToRemove = false;
public Bullet(int targetX, int targetY, String senderClass, String targetClass)
{
getImage().scale(15,3);
speed = 3;
goToX = targetX;
goToY = targetY;
mySender = senderClass;
myTarget = targetClass;
}
protected void addedToWorld(World MyWorld)
{
turnTowards(goToX, goToY);
if ( mySender == "Man") { turn(Greenfoot.getRandomNumber(4)-2); }
}
public void act()
{
move(10);
hitSomeOne();
if (hasToRemove == true)
{
getWorld().removeObject(this);
}
}
private void hitSomeOne()
{
if (canGetWorldManEnemy())
{
if ( isTouching(Enemy.class) && myTarget == "Enemy" )
{
Enemy enemy = getWorld().getObjects(Enemy.class).get(0);
enemy.hitEnemy();
hasToRemove = true;
}
else if ( isTouching(Man.class) && myTarget == "Man" )
{
Man man = getWorld().getObjects(Man.class).get(0);
man.hitMan();
hasToRemove = true;
}
//
else if (getOneIntersectingObject(Block.class) != null)
{
hasToRemove = true;
}
else
{
hasToRemove = false;
}
}
}
public String getSender()
{
return mySender;
}private int speed = 1;
private boolean permDoor = false;
private int Health;
private int hits = 0;
public Man()
{
getImage().scale(15,15);
Health = 3;
}
public void act()
{
pickKey();
passDoor();
walk(speed);
shootWhenClicked();
}
public void walk(int n)
{
int dx = 0;
int dy = 0;
if (Greenfoot.isKeyDown("d"))
{
dx++;
}
if (Greenfoot.isKeyDown("a"))
{
dx--;
}
if (Greenfoot.isKeyDown("s"))
{
dy++;
}
if (Greenfoot.isKeyDown("w"))
{
dy--;
}
for (int i = 0; i < n; i++)
{
setLocation(getX() + dx, getY());
if (getOneIntersectingObject(Block.class) != null || passDoor() )
{
setLocation(getX() - dx, getY());
}
setLocation(getX(), getY() + dy);
if (getOneIntersectingObject(Block.class) != null || passDoor() )
{
setLocation(getX(), getY() - dy);
}
}
}
private void pickKey()
{
if ( isTouching(Key.class) )
{
permDoor = true;
removeTouching(Key.class);
}
}
private boolean passDoor()
{
if (getOneIntersectingObject(Door.class) != null && permDoor != true)
{
return(true);
}
else
{
return(false);
}
}
private void shootWhenClicked()
{
if ( Greenfoot.getMouseInfo() != null)
{
if ( Greenfoot.mouseClicked(null) )
{
int MouseX = Greenfoot.getMouseInfo().getX();
int MouseY = Greenfoot.getMouseInfo().getY();
shoot(MouseX, MouseY, getX(), getY(), "Man");
}
}
}
public void hitMan()
{
Health--;
hits++;
if ( Health == 0 )
{
getWorld().removeObject(this);
}
}private int Health;
private int speed;
private int maxX;
private int minX;
private int hits = 0;
private boolean turnedAtWall = false;
private boolean turned = false;
public Enemy(int max, int min)
{
Health = 10;
speed = 1;
maxX = max;
minX = min;
}
public void act()
{
routine();
move(speed);
randomShoot();
}
private void routine()
{
if ( turned == false )
{
if (getX() > maxX)
{
turn(180);
turned = true;
}
else if (getX() < minX)
{
turn(180);
turned = true;
}
}
else
{
turned = false;
}
}
private void randomShoot()
{
if ( getWorld().getObjects(Man.class) != null)
{
if ( Greenfoot.getRandomNumber(1000) < 5 )
{
int ManX = ((Man) getWorld().getObjects(Man.class).get(0)).getX();
int ManY = ((Man) getWorld().getObjects(Man.class).get(0)).getY();
shoot(ManX, ManY, getX(), getY(), "Enemy");
}
}
}
public void hitEnemy()
{
Health--;
hits++;
if ( Health == 0 )
{
getWorld().removeObject(this);
}
}